High-order multiple-user multiple-input multiple-output operation for wireless communication systems

ABSTRACT

Methods and apparatuses schedule resources and identify resource scheduling in a MU MIMO wireless communication system. A method for identifying resource scheduling for a UE includes receiving downlink control information; identifying, from the downlink control information, one or more DM-RS ports assigned to the UE and a PDSCH EPRE to DM-RS EPRE ratio; and identifying data intended for the UE in a resource block in a downlink subframe using the one or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio. A method for scheduling resources includes identifying one or more DM-RS ports to assign to a UE and a PDSCH EPRE to DM-RS EPRE ratio for identifying data intended for the UE in a resource block in a downlink subframe; and including an indication of the one or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio in downlink control information.

CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY

The present applicationThis application is an application for reissue ofU.S. Pat. No. 9,019,924 issued Apr. 28, 2015 on U.S. patent applicationSer. No. 13/841,791 filed Mar. 15, 2013, which claims priority to U.S.Provisional Patent Application Ser. No. 61/620,318, filed Apr. 4, 2012,entitled “METHODS AND APPARATUS FOR SUPPORTING HIGH-ORDER MU-MIMOOPERATION FOR WIRELESS COMMUNICATIONS SYSTEM” and U.S. ProvisionalPatent Application Ser. No. 61/668,877, filed Jul. 6, 2012, entitled“METHODS AND APPARATUS FOR SUPPORTING HIGH-ORDER MU-MIMO OPERATION FORWIRELESS COMMUNICATIONS SYSTEM”. The content of the above-identifiedpatent documents is incorporated herein by reference.

TECHNICAL FIELD

The present application relates generally to multiple-user (MU)multiple-input multiple-output (MIMO) wireless communication systemsand, more specifically, to techniques for enabling and supporting highorder MU-MIMO operation for wireless communication systems.

BACKGROUND

In radio, MU-MIMO is a set of MIMO techniques that use multipleindependent terminals (e.g., user equipments (UEs)) in order to enhancethe communication capabilities of each UE. Standards limit the number ofUEs that are supported by MU-MIMO. For example, in release 10 of the3GPP LTE, only four MU-MIMO users may be supported.

Accordingly, there is a need for techniques for enabling and supportinghigh order MU-MIMO operation for wireless communication systems.

SUMMARY

Embodiments of the present disclosure provide methods and apparatuses toschedule resources and identify resource scheduling in a MU-MIMOwireless communication system.

In one embodiment, a method for identifying resource scheduling for a UEin a multiple-user multiple-input multiple-output wireless communicationsystem is provided. The method includes receiving downlink controlinformation. The method includes identifying, from the downlink controlinformation, one or more DM-RS ports assigned to the UE and a PDSCH EPREto DM-RS EPRE ratio. Additionally, the method includes identifying dataintended for the UE in a resource block in a downlink subframe using theone or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio. Theresource block in the downlink subframe includes data for multiple usersin the wireless communication system.

In another embodiment, a method for scheduling resources in amultiple-user multiple-input multiple-output wireless communicationsystem is provided. The method includes identifying one or more DM-RSports to assign to a UE and a PDSCH EPRE to DM-RS EPRE ratio foridentifying data intended for the UE in a resource block in a downlinksubframe. Additionally, the method includes including an indication ofthe one or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio indownlink control information. The resource block in the downlinksubframe includes data for multiple users in the wireless communicationsystem.

In yet another embodiment, an apparatus configured to identify resourcescheduling for a UE in a multiple-user multiple-input multiple-outputwireless communication system is provided. The apparatus includes areceiver configured to receive downlink control information and acontroller. The controller is configured to identify, from the downlinkcontrol information, one or more DM-RS ports assigned to the UE and aPDSCH EPRE to DM-RS EPRE ratio. Additionally, the controller isconfigured to identify data intended for the UE in a resource block in adownlink subframe using the one or more DM-RS ports and the PDSCH EPREto DM-RS EPRE ratio. The resource block in the downlink subframeincludes data for multiple users in the wireless communication system.

In another embodiment, an apparatus configured to schedule resources ina multiple-user multiple-input multiple-output wireless communicationsystem is provided. The apparatus includes a transmitter and acontroller. The controller is configured to identify one or more DM-RSports to assign to a UE and a PDSCH EPRE to DM-RS EPRE ratio foridentifying data intended for the UE in a resource block in a downlinksubframe. Additionally, the controller is configured to control thetransmitter to include an indication of the one or more DM-RS ports andthe PDSCH EPRE to DM-RS EPRE ratio in downlink control information. Theresource block in the downlink subframe includes data for multiple usersin the wireless communication system.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.Definitions for certain words and phrases are provided throughout thispatent document, those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates an exemplary wireless system which transmits messagesin accordance with an illustrative embodiment of the present disclosure;

FIG. 2A illustrates a high-level diagram of an orthogonal frequencydivision multiple access transmit path in accordance with anillustrative embodiment of the present disclosure;

FIG. 2B illustrates a high-level diagram of an orthogonal frequencydivision multiple access receive path in accordance with an illustrativeembodiment of the present disclosure;

FIG. 3 illustrates a block diagram of a transmitter and a receiver in awireless communication system that may be used to implement variousembodiments of the present disclosure;

FIGS. 4A-C illustrate examples of orthogonal or semi-orthogonal MU-MIMOmultiplexing in accordance with embodiments of the present disclosure;

FIG. 5 illustrates a signaling pattern for MU-MIMO multiplexing usingports of the same CDM group in accordance with various embodiments ofthe present disclosure;

FIG. 6 illustrates an example of orthogonal or semi-orthogonal MU-MIMOmultiplexing where the PDSCH EPRE to DM-RS EPRE ratio is assumed to be 0dB in accordance with embodiments of the present disclosure;

FIG. 7 illustrates a block diagram of a UE capable of performingadvanced multiple-user interference cancellation and/or suppression inaccordance with illustrative embodiments of the present disclosure;

FIG. 8 illustrates an indication of resource assignments for a UE havingan overlapping allocation of resource blocks in accordance with variousembodiments of the present disclosure;

FIG. 9 illustrates a process for identifying resource scheduling for aUE in a multiple-user multiple-input multiple-output wirelesscommunication system in accordance with various embodiments of thepresent disclosure; and

FIG. 10 illustrates a process for scheduling resources in amultiple-user multiple-input multiple-output wireless communicationsystem in accordance with various embodiments of the present disclosure.

DETAILED DESCRIPTION

FIGS. 1 through 10 , discussed below, and the various embodiments usedto describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

The following documents and standards descriptions are herebyincorporated into the present disclosure as if fully set forth herein:3GPP TS 36.211 v10.3.0, “E-UTRA, Physical channels and modulation;” 3GPPTS 36.212 v10.3.0, “E-UTRA, Multiplexing and Channel coding;” 3GPP TS36.213 v10.3.0, “E-UTRA, Physical Layer Procedures;” and 3GPP TS 36.214v10.1.0, “E-UTRA, Physical Layer Measurement.” The present applicationalso incorporates by reference US Patent Application Publication No.2010/0195599.

Embodiments of the present disclosure recognize that in the release 103GPP LIE demodulation reference signal (DM-RS) pattern, DM-RS ports 7,8, 11, and 13 are transmitted in the same set of resource elements (REs)with code division multiplexing (CDM) group 1, whereas DM-RS ports 9,10, 12, and 14 are transmitted in a different set of REs with CDM group2. In release 10, LTE supports up to 4 MU-MIMO users in principle, eachuser up to rank 2 in a transparent manner. However, MU is optimized forrank 1 transmission to each user where only two orthogonal ports (e.g.,ports 7 and 8—both located in CDM group 1) are used for MU-MIMOtransmission. Unless the release 10 or 11 UE is also assigned port(s) inCDM group 2, the release 10 or 11 UEs assume REs of port(s) belonging tothe CDM group 2 are used for data transmission as well. Additionally, itmay not be possible to assign rank 1 or rank 2 users to CDM group 2using the control signaling supported in release 10.

Embodiments of the present disclosure recognize that advanced wirelesscommunication systems (e.g., such as a “Massive MIMO System” or a“Full-Dimension MIMO (FD-MIMO) System”) may utilize a high number ofantenna elements at the base station tower for beamforming. Embodimentsof the present disclosure also recognize that as the number of antennaelements at the base station tower for beamforming increases, so toodoes the number of users that can be simultaneously served.

Accordingly, embodiments of the present disclosure provide methods andapparatuses to enable, support, and facilitate a high order MU-MIMOoperation. In particular, embodiments of the present disclosure providemethods and apparatuses to schedule resources and identify resourcescheduling in a MU-MIMO wireless communication system. Additionally,embodiments of the present disclosure recognize that signaling overheadand interference between UEs may cause limitations in the number ofusers that may be efficiently supported in a MU-MIMO wirelesscommunication system. Accordingly, embodiments of the present disclosureprovide methods and apparatuses to efficiently manage signaling overheadand interference between UEs to enable, support, and facilitate a highorder MU-MIMO operation.

FIGS. 1-3 below describe various embodiments implemented in wirelesscommunication systems and with the use of OFDM or OFDMA communicationtechniques. The description of FIGS. 1-3 is not meant to imply physicalor architectural limitations to the manner in which differentembodiments may be implemented. Different embodiments of the presentdisclosure may be implemented in any suitably arranged communicationssystem.

FIG. 1 illustrates exemplary wireless system 100, which transmitsmessages according to the principles of the present disclosure. In theillustrated embodiment, wireless system 100 includes transmission points(e.g., an Evolved Node B (eNB), Node B), such as base station (BS) 101,base station (BS) 102, base station (BS) 103, and other similar basestations or relay stations (not shown). Base station 101 is incommunication with base station 102 and base station 103. Base station101 is also in communication with Internet 130 or a similar IP-basedsystem (not shown).

Base station 102 provides wireless broadband access (via base station101) to Internet 130 to a first plurality of UEs (e.g., mobile phone,mobile station, subscriber station) within coverage area 120 of basestation 102. The first plurality of UEs includes UE 111, which may belocated in a small business (SB); UE 112, which may be located in anenterprise (E); UE 113, which may be located in a WiFi hotspot (HS); UE114, which may be located in a first residence (R); UE 115, which may belocated in a second residence (R); and UE 116, which may be a mobiledevice (M), such as a cell phone, a wireless laptop, a wireless PDA, orthe like.

Base station 103 provides wireless broadband access (via base station101) to Internet 130 to a second plurality of UEs within coverage area125 of base station 103. The second plurality of UEs includes UE 115 andUE 116. In an exemplary embodiment, base stations 101-103 maycommunicate with each other and with UE 111-116 using OFDM or OFDMAtechniques.

While only six UEs are depicted in FIG. 1 , it is understood thatwireless system 100 may provide wireless broadband access to additionalUEs. It is noted that UE 115 and UE 116 are located on the edges of bothcoverage area 120 and coverage area 125. UE 115 and UE 116 eachcommunicate with both base station 102 and base station 103 and may besaid to be operating in handoff mode, as known to those of skill in theart.

UEs 111-116 may access voice, data, video, video conferencing, and/orother broadband services via Internet 130. In an exemplary embodiment,one or more of UEs 111-116 may be associated with an access point (AP)of a WiFi WLAN. UE 116 may be any of a number of mobile devices,including a wireless-enabled laptop computer, personal data assistant,notebook, handheld device, or other wireless-enabled device. UEs 114 and115 may be, for example, a wireless-enabled personal computer (PC), alaptop computer, a gateway, or another device.

FIG. 2A is a high-level diagram of transmit path circuitry 200. Forexample, the transmit path circuitry 200 may be used for an orthogonalfrequency division multiple access (OFDMA) communication. FIG. 2B is ahigh-level diagram of receive path circuitry 250. For example, thereceive path circuitry 250 may be used for an orthogonal frequencydivision multiple access (OFDMA) communication. In FIGS. 2A and 2B, fordownlink communication, the transmit path circuitry 200 may beimplemented in base station (BS) 102 or a relay station, and the receivepath circuitry 250 may be implemented in a UE (e.g. UE 116 of FIG. 1 ).In other examples, for uplink communication, the receive path circuitry250 may be implemented in a base station (e.g. base station 102 of FIG.1 ) or a relay station, and the transmit path circuitry 200 may beimplemented in a UE (e.g. UE 116 of FIG. 1 ).

Transmit path circuitry 200 comprises channel coding and modulationblock 205, serial-to-parallel (S-to-P) block 210, Size N Inverse FastFourier Transform (IFFT) block 215, parallel-to-serial (P-to-S) block220, add cyclic prefix block 225, and up-converter (UC) 230. Receivepath circuitry 250 comprises down-converter (DC) 255, remove cyclicprefix block 260, serial-to-parallel (S-to-P) block 265, Size N FastFourier Transform (FFT) block 270, parallel-to-serial (P-to-S) block275, and channel decoding and demodulation block 280.

At least some of the components in FIGS. 2A and 2B may be implemented insoftware, while other components may be implemented by configurablehardware or a mixture of software and configurable hardware. Inparticular, it is noted that the FFT blocks and the IFFT blocksdescribed in this disclosure document may be implemented as configurablesoftware algorithms, where the value of Size N may be modified accordingto the implementation.

Furthermore, although this disclosure is directed to an embodiment thatimplements the Fast Fourier Transform and the Inverse Fast FourierTransform, this is by way of illustration only and should not beconstrued to limit the scope of the disclosure. It will be appreciatedthat in an alternate embodiment of the disclosure, the Fast FourierTransform functions and the Inverse Fast Fourier Transform functions mayeasily be replaced by Discrete Fourier Transform (DFT) functions andInverse Discrete Fourier Transform (IDFT) functions, respectively. Itwill be appreciated that for DFT and IDFT functions, the value of the Nvariable may be any integer number (i.e., 1, 2, 3, 4, etc.), while forFFT and IFFT functions, the value of the N variable may be any integernumber that is a power of two (i.e., 1, 2, 4, 8, 16, etc.).

In transmit path circuitry 200, channel coding and modulation block 205receives a set of information bits, applies coding (e.g., Turbo coding)and modulates (e.g., Quadrature Phase Shift Keying (QPSK) or QuadratureAmplitude Modulation (QAM)) the input bits to produce a sequence offrequency-domain modulation symbols. Serial-to-parallel block 210converts (i.e., de-multiplexes) the serial modulated symbols to paralleldata to produce N parallel symbol streams where N is the IFFT/FFT sizeused in BS 102 and UE 116. Size N IFFT block 215 then performs an IFFToperation on the N parallel symbol streams to produce time-domain outputsignals. Parallel-to-serial block 220 converts (i.e., multiplexes) theparallel time-domain output symbols from Size N IFFT block 215 toproduce a serial time-domain signal. Add cyclic prefix block 225 theninserts a cyclic prefix to the time-domain signal. Finally, up-converter230 modulates (i.e., up-converts) the output of add cyclic prefix block225 to RF frequency for transmission via a wireless channel. The signalmay also be filtered at baseband before conversion to RF frequency.

The transmitted RF signal arrives at UE 116 after passing through thewireless channel, and reverse operations to those at BS 102 areperformed. Down-converter 255 down-converts the received signal tobaseband frequency, and remove cyclic prefix block 260 removes thecyclic prefix to produce the serial time-domain baseband signal.Serial-to-parallel block 265 converts the time-domain baseband signal toparallel time-domain signals. Size N FFT block 270 then performs an FFTalgorithm to produce N parallel frequency-domain signals.Parallel-to-serial block 275 converts the parallel frequency-domainsignals to a sequence of modulated data symbols. Channel decoding anddemodulation block 280 demodulates and then decodes the modulatedsymbols to recover the original input data stream.

Each of base stations 101-103 may implement a transmit path that isanalogous to transmitting in the downlink to UEs 111-116 and mayimplement a receive path that is analogous to receiving in the uplinkfrom UEs 111-116. Similarly, each one of UEs 111-116 may implement atransmit path corresponding to the architecture for transmitting in theuplink to base stations 101-103 and may implement a receive pathcorresponding to the architecture for receiving in the downlink frombase stations 101-103.

FIG. 3 illustrates a block diagram of a transmitter 305 and a receiver310 in a wireless communication system that may be used to implementvarious embodiments of the present disclosure. In this illustrativeexample, the transmitter 305 and the receiver 310 are devices at acommunication point in a wireless communications system, such as, forexample, wireless system 100 in FIG. 1 . In some embodiments, thetransmitter 305 or the receiver 310 may be a network entity, such as abase station, e.g., evolved node B (eNB), or remote-radio head, a relaystation, or underlay base station; gateway (GW); or base stationcontroller (BSC). In other embodiments, the transmitter 305 or thereceiver 310 may be a UE (e.g., mobile station, subscriber station,etc.). In one example, the transmitter 305 or the receiver 310 is anexample of one embodiment of the UE 116 in FIG. 1 . In another example,the transmitter 305 or the receiver 310 is an example of one embodimentof the base station 102 in FIG. 1 .

The transmitter 305 comprises antenna array 315, phase shifters 320, TXprocessing circuitry 325, and controller 330. The transmitter 305receives analog or digital signals from outgoing baseband data.Transmitter 305 encodes, multiplexes, and/or digitizes the outgoingbaseband data to produce a processed RF signal that is sent and/ortransmitted via transmitter 305. For example, the TX processingcircuitry 325 may implement a transmit path that is analogous to thetransmit processing circuitry 200 in FIG. 2 . Transmitter 305 may alsoperform spatial multiplexing via layer mapping to different antennas inantenna array 315 to transmit signals in multiple different beams. Thecontroller 330 controls the overall operation of transmitter 305. In onesuch operation, controller 330 controls the transmission of signals bythe transmitter 305, in accordance with well-known principles.

Receiver 310 receives from antenna(s) 335 an incoming RF signal orsignals transmitted by one or more transmission points, such as basestations, relay stations, remote radio heads, UEs, etc. Receiver 310includes RX processing circuitry 345 that processes the receivedsignal(s) to identify the information transmitted by the transmissionpoint(s). For example, the Rx processing circuitry 345 may down-convertthe incoming RF signal(s) to produce an intermediate frequency (IF) or abaseband signal by channel estimating, demodulating, stream separating,filtering, decoding, and/or digitizing the received signal(s). Forexample, the Rx processing circuitry 345 may implement a receive paththat is analogous to the receive processing circuitry 250 in FIG. 2B.The controller 350 controls the overall operation of the receiver 310.In one such operation, the controller 350 controls the reception ofsignals by the receiver 310, in accordance with well-known principles.

The illustration of transmitter 305 and receiver 310 illustrated in FIG.3 is for the purposes of illustrating one embodiment in whichembodiments of the present disclosure may be implemented. Otherembodiments of the transmitter 305 and the receiver 310 could be usedwithout departing from the scope of this disclosure. For example, thetransmitter 305 may be located in communication node (e.g., BS, UT, RS,and RRH) that also includes a receiver, such as receiver 310. Similarly,the receiver 310 may be located in communication node (e.g., BS, UE, RS,and RRH) that also includes a transmitter, such as transmitter 305.Antennas in the TX and RX antenna arrays in this communication node mayoverlap or be the same antenna arrays used for transmission andreception via one or more antenna switching mechanisms.

In release 10 LIE, up to four MU-MIMO users may be supported inprinciple. For example, each user up to rank 2 and only two orthogonalports (e.g., ports 7 and 8) may be used for MU-MIMO transmission.

For high-order MU-MIMO, the number of users simultaneously served by theBS can be increased significantly (e.g., 8, 10, 16, etc.). To enhanceown channel estimation quality and also to enable MU interferencesuppression/cancellation, the number of orthogonal ports for MU-MIMOtransmission can be increased, for example, to eight. To achieve this,eight orthogonal DM-RS ports (e.g., ports 7-14) are provided where thepseudorandom sequence generator is initialized according to equation 1below.c_(init)=(└n_(s)/2┘+1)·(2N_(ID) ^(cell)+1)·2¹⁶+n_(SCID)  (Equation 1)where C_(init) is the initialization value of the scrambling sequence,N_(ID) ^(cell) is the cell identifier (ED) and n_(SCID) is thescrambling code. The scrambling sequence itself can be generatedaccording to 3GPP TS 36.211 §6.10.3.1. As each DM-RS port has twoscrambling IDs (N_(ID) ^(cell)), two semi-orthogonal DM-RS resources areprovided and the total number of users that can be simultaneously servedby the base station is 16, with a rank 1 transmission to each user. Ifthe cell identifier in the DM-RS pseudorandom sequence generationinitialization is replaced with a parameter “x”, which is configurableby the network entity, (e.g. by an RRC) then the total number of usersthat can be simultaneously served by the base station can be furtherincreased.

FIGS. 4A-C illustrate examples of orthogonal or semi-orthogonal MU-MIMOmultiplexing in accordance with embodiments of the present disclosure.FIG. 4A illustrates a frequency resource for two RS orthogonally orsemi-orthogonally multiplexed to provide one reference signal per UE totwo UEs and the corresponding multiplexing of the frequency resourcesfor the data intended for the respective UEs. FIG. 4B illustrates twofrequency resources used for two RSs for three UEs with data intendedfor the respective UEs orthogonally or semi-orthogonally multiplexedamong the frequency resources for data. FIG. 4C illustrates twofrequency resources for eight RSs orthogonally or semi-orthogonallymultiplexed to provide reference signals to eight UEs. The data for theUEs is orthogonally or semi-orthogonally multiplexed among the frequencyresources for data. In various embodiments, the network entity mayassign the DM-RS resources such that UEs with relatively higherinter-user interference have orthogonal DM-RS resources, while UEs withrelatively low inter-user interference may be assigned DM-RS resourcesthat are semi-orthogonal.

FIG. 5 illustrates a signaling pattern for MU-MIMO multiplexing usingports of a same CDM group in accordance with various embodiments of thepresent disclosure. To facilitate MU-MIMO multiplexing between UEs,various embodiments include assignment of ports belonging to a same CDMgroup (e.g., ports 11 and 13). In other words, in one physical resourceblock (PRB), the DM-RS ports used by the network entity for MU-MIMOmultiplexing may include only ports of the same CDM group, for example,ports 7, 8, 11, and 13 as illustrated in FIG. 5 , while the portsbelonging to different CDM group (e.g., ports 9, 10, 12, and 14) are nottransmitted, and the corresponding REs may be used for datatransmission. An additional advantage of this design is that theoverhead for the DM-RS may be reduced.

Additionally, this design also does not impact the PDSCH EPRE to DM-RSEPRE ratio assumed by legacy UEs (e.g., assumed to be 0 dB). The highorder MU-MIMO UEs can also assume that the PDSCH EPRE to DM-RS EPREratio is 0 dB. For example, FIG. 6 illustrates an example of orthogonalor semi-orthogonal MU-MIMO multiplexing where the PDSCH EPRE to DM-RSEPRE ratio is assumed to be 0 dB in accordance with embodiments of thepresent disclosure.

In some embodiments, the resource elements for the UEs may bemultiplexed using only two ports (e.g., ports 7 and 8), for example, byassigning different scrambling ID for different UEs assigned the sameDM-RS port.

Additionally, in various embodiments, DM-RS ports of CDM group 2 may beused for MU-MIMO multiplexing by the network entity if one or more DM-RSports of CDM group 1 are also used. In one example, if a UE is assignedonly port(s) from CDM group 2, the UE may assume that the REscorresponding to the DM-RS of CDM group 1 are not used for datatransmission. This use of DM-RS ports of CDM group 2 also enables a UEto be multiplexed with a legacy UE that is assigned with rank that isgreater than 2.

In various embodiments, the network entity may provide control signalingto indicate the scheduling of the resources to support the high-orderMU-MIMO operations of the present disclosure. The control signalingprovided by the network entity may include at least one and possiblymore of: the DM-RS Port(s) assigned to the UE; a physical downlinkshared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPREratio; whether rate matching around unassigned port(s) in another DM-RSCDM group should be applied; and the existence of interfering UEs.

The PDSCH EPRE to DM-RS EPRE ratio is a ratio of the average power ofthe signal intended for the UE compared with the average power ofanother signal that may be present in the resource element. For example,a signal in a resource element intended for a UE may be separated anddistinguished from a signal in the same resource element that isintended to convey different information than the other signal based onthe PDSCH EPRE to DM-RS EPRE ratio (e.g., a −3 dB average powerdifference between the signals). Even if UE is assigned 2 or less than 2layers, other DM-RS CDM groups may be assigned to other UEs. If the UEis not assigned any ports belonging to a DM-RS CDM group, the controlsignaling may indicate whether the UE should assume data is mapped tothe REs of that DM-RS CDM group or not (e.g., whether rate matchingaround unassigned port(s) in another DM-RS CDM group should be applied).The control signaling may also indicate the existence of interferingUEs. For example, the control signaling from the network entity mayindicate whether the DM-RS port(s) not assigned to the UE is assigned toanother UE. The explicit signaling of interfering UEs may avoid the needfor the UE to use blind detection of the existence of an interfering UE.

In various embodiments, the network entity may enable dynamic singleuser (SU) and MU scheduling. For example, a base station may providedynamic control signaling (e.g. provided in a downlink controlinformation (DCI) format) which can be supported to indicate whether SUor MU scheduling is being used.

Indicating the DM-RS ports, the PDSCH EPRE to DM-RS EPRE ratio, ratematching, and the existence of interfering UEs may require significantsignaling overhead to fully support and enable MU-MIMO operation.Various embodiments utilize signaling techniques to reduce the signalingoverhead associated with implementing the MU-MIMO operation of thepresent disclosure. For example, in some embodiments, the network entitymay only assign each MU-MIMO UE up to rank 2 spatial multiplexing andmay jointly code the power offset and rate matching. For example, asingle bit field may jointly indicate the power offset and rate matchingassumption. In one illustrative embodiment, the network entity mayintroduce or reuse one bit from an existing bit in the DCI format toindicate the power offset and rate matching, for example, as shown inTable 1 below. In another example, this information can be jointlyencoded with other fields, for example, a bit field used to indicateantenna port(s), scrambling identity, and/or number of layers may alsobe used to jointly indicate the power offset and/or rate matchingassumption.

TABLE 1 Power offset and rate matching signaling PDSCH EPRE Ratematching Signaled to DM-RS around not assigned value EPRE ratio CDMgroup 0  0 dB No 1 −3 dB Yes

In some embodiments, if the UE is assigned port(s) that are not DM-RSports 7 and/or 8, the UE may assume that the PDSCH EPRE-to-DM-RS EPREratio of −3 dB and rate matching applied when receiving PDSCH in theassigned resource blocks. If UE is assigned ports 7 and/or 8, thenetwork entity may provide additional signaling to indicate what PDSCHEPRE-to-DM-RS EPRE ratio and rate matching are to be assumed.

In other embodiments, if UE is assigned port(s) that do not belong toDM-RS CDM group 1, the UE may assume a PDSCH EPRE-to-DM-RS EPRE ratio of−3 dB and rate matching around REs belonging to DM-RS CDM group 1 whenreceiving PDSCH in the assigned resource blocks. If UE is only assignedports in CDM group 1 and not in CDM group 2, the network entity mayprovide additional signaling to indicate what PDSCH EPRE to DM-RS EPREratio and whether rate matching around REs belonging to CDM group 2 areto be assumed. In these embodiments, DM-RS CDM group 1 is implicitlyprioritized for assignment.

In one example, the baseline DCI format design can be similar to DCIformat 2C in release 10, with at least the following exception: the bitfield used for joint coding of antenna port(s), scrambling identity andnumber of layers is extended to allow enhanced support for MU-MIMO (seee.g., Tables 2 and 3 where 5 bits are used). One example of the DM-RSmapping as described above is also illustrated in these tables. Forexample, for one codeword transmission, the power offset and ratematching can be indicated by an existing field reserved for the secondcodeword, (e.g. the New Data Indicator (NDI) of the disabled TB). Oneexample of the extension of bit field used for joint coding of antennaport(s), scrambling identity, and number of layers for one codewordtransmission is illustrated in Table 2 below.

TABLE 2 One Codeword: Codeword 0 enabled, Codeword 1 disabled ValueMessage 0 1 layer, port 7, n_(SCID) = 0 1 1 layer, port 7, n_(SCID) = 12 1 layer, port 8, n_(SCID) = 0 3 1 layer, port 8, n_(SCID) = 1 4 2layers, ports 7-8, n_(SCID) = 0 5 3 layers, ports 7-9 (−3 dB PO) 6 4layers, ports 7-10 (−3 dB PO) 7 1 layer, port 9, n_(SCID) = 0 8 1 layer,port 9, n_(SCID) = 1 9 1 layer, port 10, n_(SCID) = 0 10 1 layer, port10, n_(SCID) = 1 11 1 layer, port 11, n_(SCID) = 0 12 1 layer, port 11,n_(SCID) = 1 13 1 layer, port 12, n_(SCID) = 0 14 1 layer, port 12,n_(SCID) = 1 15 1 layer, port 13, n_(SCID) = 0 16 1 layer, port 13,n_(SCID) = 1 17 1 layer, port 14, n_(SCID) = 0 18 1 layer, port 14,n_(SCID) = 1 19 2 layers, ports 7-8, n_(SCID) = 1 20 2 layers, ports9-10, n_(SCID) = 0 21 2 layers, ports 9-10, n_(SCID) = 1 22 2 layers,ports 11, 13, n_(SCID) = 0 23 2 layers, ports 11, 13, n_(SCID) = 1 24 2layers, ports 12, 14, n_(SCID) = 0 25 2 layers, ports 12, 14, n_(SCID) =1 26 Reserved 27 Reserved 28 Reserved 29 Reserved 30 Reserved 31Reserved

For more than two layer transmissions, if only −3 dB power offset issupported, the bit to indicate power offset value may be ignored by theUE. For two-codeword transmission, the power offset and rate matchingassumption can also be jointly encoded with the antenna port(s),scrambling identity, and number of layers as there are enough reservedbits, as shown in Table 3 below. One example of the extension of bitfield used for joint coding of antenna port(s), scrambling identity, andnumber of layers for two codeword transmission is illustrated in Table3.

TABLE 3 Two Codewords: Codeword 0 enabled, Codeword 1 enabled ValueMessage 0 2 layers, ports 7-8, n_(SCID) = 0 (0 dB PO) 1 2 layers, ports7-8, n_(SCID) = 1 (0 dB PO) 2 3 layers, ports 7-9 (−3 dB PO) 3 4 layers,ports 7-10 (−3 dB PO) 4 5 layers, ports 7-11 (−3 dB PO) 5 6 layers,ports 7-12 (−3 dB PO) 6 7 layers, ports 7-13 (−3 dB PO) 7 8 layers,ports 7-14 (−3 dB PO) 8 2 layers, ports 9-10, n_(SCID) = 0, −3 dB PO &RM 9 2 layers, ports 9-10, n_(SCID) = 1, −3 dB PO & RM 10 2 layers,ports 11, 13, n_(SCID) = 0, −3 dB PO & RM 11 2 layers, ports 11, 13,n_(SCID) = 1, −3 dB PO & RM 12 2 layers, ports 12, 14, n_(SCID) = 0, −3dB PO & RM 13 2 layers, ports 12, 14, n_(SCID) = 1, −3 dB PO & RM 14 2layers, ports 7-8, n_(SCID) = 0, −3 dB PO & RM 15 2 layers, ports 7-8,n_(SCID) = 1, −3 dB PO & RM 16 2 layers, ports 11, 13, n_(SCID) = 0 (0dB PO) 17 2 layers, ports 11, 13, n_(SCID) = 1 (0 dB PO) 18 Reserved 19Reserved 20 Reserved 21 Reserved 22 Reserved 23 Reserved 24 Reserved 25Reserved 26 Reserved 27 Reserved 28 Reserved 29 Reserved 30 Reserved 31Reserved

In other examples, the power offset and rate matching information canalso be jointly encoded with the antenna port(s), scrambling ID, andnumber of layers regardless of the number of codewords assigned (e.g.,the bit field can be extended to 6 bits). Other alternatives, such asjoint encoding of antenna port(s), number of layers and power offset(PO) and rate matching (RM) information instead, and a separate bit forscrambling ID may also be used.

In another example, joint coding of antenna port(s), scramblingidentity, number of layers, power offset, and rate matching assumptionmay be indicated as illustrated in the exemplary coding format in Table4 and Table 5 for one codeword assignment and two codewords assignment,respectively. In these examples, the one advantage is that only 5 bitsmay be needed to include the power offset and rate matching information.

One example of joint encoding of antenna port(s), scrambling identity,number of layers, PDSCH EPRE to DM-RS power ratio, and rate matching forone codeword transmissions is illustrated in Table 4 below.

TABLE 4 One Codeword: Codeword 0 enabled, Codeword 1 disabled ValueMessage 0 1 layer, port 7, n_(SCID) = 0 (0 dB PO) 1 1 layer, port 7,n_(SCID) = 1 (0 dB PO) 2 1 layer, port 8, n_(SCID) = 0 (0 dB PO) 3 1layer, port 8, n_(SCID) = 1 (0 dB PO) 4 2 layers, ports 7-8, n_(SCID) =0 (0 dB PO) 5 3 layers, ports 7-9 (−3 dB PO) 6 4 layers, ports 7-10 (−3dB PO) 7 1 layer, port 9, n_(SCID) = 0, −3 dB PO & RM 8 1 layer, port 9,n_(SCID) = 1, −3 dB PO & RM 9 1 layer, port 10, n_(SCID) = 0, −3 dB PO &RM 10 1 layer, port 10, n_(SCID) = 1, −3 dB PO & RM 11 1 layer, port 11,n_(SCID) = 0, −3 dB PO & RM 12 1 layer, port 11, n_(SCID) = 1, −3 dB PO& RM 13 1 layer, port 12, n_(SCID) = 0, −3 dB PO & RM 14 1 layer, port12, n_(SCID) = 1, −3 dB PO & RM 15 1 layer, port 13, n_(SCID) = 0, −3 dBPO & RM 16 1 layer, port 13, n_(SCID) = 1, −3 dB PO & RM 17 1 layer,port 14, n_(SCID) = 0, −3 dB PO & RM 18 1 layer, port 14, n_(SCID) = 1,−3 dB PO & RM 19 2 layers, ports 7-8, n_(SCID) = 1 (0 dB PO) 20 2layers, ports 9-10, n_(SCID) = 0, −3 dB PO & RM 21 2 layers, ports 9-10,n_(SCID) = 1, −3 dB PO & RM 22 2 layers, ports 11, 13, n_(SCID) = 0, −3dB PO & RM 23 2 layers, ports 11, 13, n_(SCID) = 1, −3 dB PO & RM 24 2layers, ports 12, 14, n_(SCID) = 0, −3 dB PO & RM 25 2 layers, ports 12,14, n_(SCID) = 1, −3 dB PO & RM 26 1 layer, port 7, n_(SCID) = 0, −3 dBPO & RM 27 1 layer, port 7, n_(SCID) = 1, −3 dB PO & RM 28 1 layer, port8, n_(SCID) = 0, −3 dB PO & RM 29 1 layer, port 8, n_(SCID) = 1, −3 dBPO & RM 30 2 layers, ports 7-8, n_(SCID) = 0, −3 dB PO & RM 31 2 layers,ports 7-8, n_(SCID) = 1, −3 dB PO & RM

One example of joint encoding of antenna port(s), scrambling identity,number of layers, PDSCH EPRE to DM-RS power ratio and rate matching fortwo codeword transmissions is illustrated in Table 5 below.

TABLE 5 Two Codewords: Codeword 0 enabled, Codeword 1 enabled ValueMessage 0 2 layers, ports 7-8, n_(SCID) = 0 (0 dB PO) 1 2 layers, ports7-8, n_(SCID) = 1 (0 dB PO) 2 3 layers, ports 7-9 (−3 dB PO) 3 4 layers,ports 7-10 (−3 dB PO) 4 5 layers, ports 7-11 (−3 dB PO) 5 6 layers,ports 7-12 (−3 dB PO) 6 7 layers, ports 7-13 (−3 dB PO) 7 8 layers,ports 7-14 (−3 dB PO) 8 2 layers, ports 9-10, n_(SCID) = 0, −3 dB PO &RM 9 2 layers, ports 9-10, n_(SCID) = 1, −3 dB PO & RM 10 2 layers,ports 11, 13, n_(SCID) = 0, −3 dB PO & RM 11 2 layers, ports 11, 13,n_(SCID) = 1, −3 dB PO & RM 12 2 layers, ports 12, 14, n_(SCID) = 0, −3dB PO & RM 13 2 layers, ports 12, 14, n_(SCID) = 1, −3 dB PO & RM 14 2layers, ports 7-8, n_(SCID) = 0, −3 dB PO & RM 15 2 layers, ports 7-8,n_(SCID) = 1, −3 dB PO & RM 16 2 layers, ports 11, 13, n_(SCID) = 0 (0dB PO) 17 2 layers, ports 11, 13, n_(SCID) = 1 (0 dB PO) 18 Reserved 19Reserved 20 Reserved 21 Reserved 22 Reserved 23 Reserved 24 Reserved 25Reserved 26 Reserved 27 Reserved 28 Reserved 29 Reserved 30 Reserved 31Reserved

In another example, if two layer transmission is not supported by theDCI format, joint encoding of antenna port(s), scrambling identity,number of layers, PDSCH EPRE to DM-RS power ratio, and rate matching maystill be accomplished as illustrated, for example, in Table 6. Oneexample of joint encoding of antenna port(s), scrambling identity,number of layers, PDSCH EPRE to DM-RS power ratio, and rate matching forone codeword transmissions is illustrated in Table 6 below.

TABLE 6 One Codeword: Codeword 0 Value Message  0 1 layer, port 7,n_(SCID) = 0 (0 dB PO)  1 1 layer, port 7, n_(SCID) = 1 (0 dB PO)  2 1layer, port 8, n_(SCID) = 0 (0 dB PO)  3 1 layer, port 8, n_(SCID) = 1(0 dB PO)  4 1 layer, port 7, n_(SCID) = 0, −3 dB PO & RM  5 1 layer,port 7, n_(SCID) = 1, −3 dB PO & RM  6 1 layer, port 8, n_(SCID) = 0, −3dB PO & RM  7 1 layer, port 8, n_(SCID) = 1, −3 dB PO & RM  8 1 layer,port 9, n_(SCID) = 0, −3 dB PO & RM  9 1 layer, port 9, n_(SCID) = 1, −3dB PO & RM 10 1 layer, port 10, n_(SCID) = 0, −3 dB PO & RM 11 1 layer,port 10, n_(SCID) = 1, −3 dB PO & RM 12 1 layer, port 11, n_(SCID) = 0(0 dB PO) 13 1 layer, port 11, n_(SCID) = 1 (0 dB PO) 14 1 layer, port11, n_(SCID) = 0, −3 dB PO & RM 15 1 layer, port 11, n_(SCID) = 1, −3 dBPO & RM 16 1 layer, port 12, n_(SCID) = 0, −3 dB PO & RM 17 1 layer,port 12, n_(SCID) = 1, −3 dB PO & RM 18 1 layer, port 13, n_(SCID) = 0(0 dB PO) 19 1 layer, port 13, n_(SCID) = 1 (0 dB PO) 20 1 layer, port13, n_(SCID) = 0, −3 dB PO & RM 21 1 layer, port 13, n_(SCID) = 1, −3 dBPO & RM 22 1 layer, port 14, n_(SCID) = 0, −3 dB PO & RM 23 1 layer,port 14, n_(SCID) = 1, −3 dB PO & RM 24 Reserved . . . . . . . . . . . .31 Reserved

Various embodiments of the present disclosure provide advanced MUinterference suppression and/or cancellation support. For example, ifadvanced MU interference cancellation/suppression is supported by theUE, the network entity may indicate one or more of the following to theUE: the modulation and coding scheme (MCS) of interfering UEs (aninterfering UE assigned with rank 2 may be identified as two virtualinterfering UEs of rank 1), port(s) of interfering UEs, the number ofinterfering UEs, UE ID (e.g., C-RNTI) of interfering UEs, and/or theDM-RS port scrambling ID of the interfering UEs. In these interferencereduction examples, signaling overhead may be reduced and/or managed bysignaling the information of only the interfering UEs that are stronginterferers or have an interference over a threshold. In other words,not all the information of all interfering UEs may be signaled to reducesignaling overhead. For example, interfering UEs that are assignedorthogonal DM-RS ports with respect to the desired UE may not beconsidered as UEs that are strong interferers.

FIG. 7 illustrates a block diagram of a UE 700 capable of performingadvanced multi-user interference cancellation and/or suppression inaccordance with illustrative embodiments of the present disclosure. Forexample, as illustrated, the de-multiplexer 705, channel estimator 710,and/or the MIMO (SU or MU) receiver 715 may utilize the informationabout the interfering UEs that was signaled in the control informationreceived from the network entity as described above. To enable theadvanced multi-user interference cancellation and/or suppression, thede-multiplexer 705 may receive signals from multiple ports. The channelestimator 710 may receive and estimate the channel using the RS of LTE700 and the interfering UE(s). The MIMO receiver 715 receives thechannel estimate from the channel estimator 710 and uses the estimate ofthe channel to reduce interference that may be present in the signalsintended to be received by the UE. The demodulator 720 demodulates thereceived signals for decoding of the received signal by the decoder 725.

Additionally or alternatively, in various embodiments, the UE 700 mayinclude a feedback loop 730 for canceling and/or subtractinginterference of interfering UE(s) from the received signal. For example,given that the UE 700 information about the interfering UE(s), the UE700 can decode and reconstruct the interfering signal(s), which can befed back to the MIMO receiver 715 to subtract the interfering signal(s)for interference cancellation/suppression. Whether the UE 700 includesthe feedback loop 730 canceling and/or subtracting interference ofinterfering UE(s) in addition to or instead of the interferencesuppression techniques described above is an implementation choice andembodiments of the present disclosure may include any combination of thecancellation and/or suppression techniques described herein.

The control signaling for interference reduction can be provided in adynamic manner via DCI signaling. In one example embodiment, reductionin signaling overhead may be achieved by associating each DM-RS portwith a port scrambling ID for PDSCH. In particular, PDSCH transmittedusing a DM-RS port is scrambled with its port scrambling ID instead ofthe C-RNTI of the UE. For example, the initialization value of thescrambling sequence may be calculated as provided in equation 2 below:c_(init)=n_(Port-ID)·2¹⁴+q·2¹³+└n_(s)/2┘·2⁹N_(ID) ^(cell)  (Equation 2)where n_(Port-ID) is the DM-RS port scrambling ID. Signaling of theinterfering UE's DM-RS port scrambling ID has significantly loweroverhead than signaling of C-RNTI. For example, if 8 ports are defined,only 3 bits are required for signaling of the DM-RS port scrambling ID,compared to 16 bits for C-RNTI signaling.

In another embodiment, only one codeword/transport block may be assignedto the desired UE. The bit field of the unused transport block in theDCI format (e.g. 2C/2D) may be used or reused to indicate theinformation of the interfering UE. In one example, assuming onlytransport block 1 is assigned to a UE, the MCS field of transport block2 can be used to indicate the MCS of the interfering UE. The redundancyversion and the NDI bits (3 bits total) for transport block 2 can alsobe used or reused to indicate the DM-RS port index of the interferingUE. One example of reinterpretation of fields in DCI format (e.g. 2C/2D)is illustrated in Table 7 below.

TABLE 7 Field in DCI format (e.g. 2C/2D) Interpretation MCS of TB 2 MCSof interfering UE RV and NDI of TB2 Port index of interfering UE

FIG. 8 illustrates an indication of resource assignments for a UE havingan overlapping allocation of resource blocks in accordance with variousembodiments of the present disclosure. To effectively enableinterference cancellation as described above, UEs may be scheduled withan overlapping allocation of RBs in frequency. While this schedulingscheme may somewhat limit scheduling flexibility, this scheduling schememay reduce the signaling overhead for interference reduction. Forexample, the network entity may define a group of RBs over which thesame set of UEs is allocated the same set of DMRS ports. Since theamount of coded data sent to each UE may be different, a UE may have tofurther detect the presence or absence of a UE allocation in the RBs onthe assigned port.

In one example, the network entity may signal information related to theresource allocation information of a co-scheduled UE. In DCI Format 2C,the 3GPP Specification 36.212 describes the signaling of resourceallocation to a UE. A resource allocation header (resource allocationtype 0/type 1)—1 bit as defined in section 7.1.6 (of 36.213). Ifdownlink bandwidth is less than or equal to 10 PRBs, there is noresource allocation header, and resource allocation type 0 is assumed.Resource block assignment: for resource allocation type 0 as defined insection 7.1.6.1 of [36.213] and ┌N_(RB) ^(DL)/P┐ bits provide theresource allocation; for resource allocation type 1 as defined insection 7.1.6.2 (of 36.213) ┌ log₂(P)┐ bits of this field are used as aheader specific to this resource allocation type to indicate theselected resource blocks subset, 1 bit indicates a shift of the resourceallocation span, and (┌N_(RB) ^(DL)/P┐−┌ log₂(P)┐−1) bits provide theresource allocation, where the value of P depends on the number of DLresource blocks as indicated in section 7.1.6.1 (of 36.213).

The resource allocation defined includes a bitmap or a selection from aset of localized or distributed resource blocks and virtual resourceblocks or resource block groups. This resource allocation allowssufficient flexibility to share the resources in frequency to differentUEs. Further, a resource allocation header indicates a selection betweenthe resource allocation types.

To enable support for interference cancellation, some furthercoordination of resource allocation may be useful. In variousembodiments, a co-channel resource allocation block assignment field andco-channel resource allocation header may be defined to indicate theresource allocation information of a co-scheduled UE. In theseembodiments, the UE may assume the interference from that UE only in theset of overlapping resources. For example, as illustrated in FIG. 8 ,the UE assumes interference from only the co-scheduled/overlappingblocks and no interference is assumed in the non-overlapping blocks.

In another example, the set of overlapping resources over which aninterfering UE is scheduled may be directly indicated with a resourceallocation header and a resource block assignment field. In anotherexample, the set of overlapping resources over which an interfering UEis not scheduled may be directly indicated with a resource allocationheader and a resource block assignment field. In another example, a setof resource assignments may be pre-defined (e.g., by higher layersignaling or fixed) and dynamic signaling may be used to select betweenthe different resource assignments to reduce overhead in DCI. In anotherexample, co-channel resource allocation may be implicitly determined bythe UE using one or more of the other parameters signaled for the otherUE, (e.g., port index, port RNTI, a pre-configured group ID forsimilarly scheduled UEs). In these examples, the indicated resourceallocation corresponds to the resources over which the UE can expectinterference and the associated signaled interference reductionparameters (e.g., MCS, port RNTI, port ID, etc.) are applicable.

In various embodiments, the base station may transmit the PDSCH usingDM-RS ports that are scrambled with the port's scrambling ID instead ofthe C-RNTI of the UE, and the network entity assigns each DM-RS port adifferent port scrambling ID. In one example, the scramblinginitialization equation may be calculated according to equation 3 below:c_(init)=n_(Port-ID)·2¹⁴+q·2¹³+└n_(s)/2┘·2⁹+N_(ID) ^(cell)  (Equation 3)where n_(Port-ID) is the DM-RS port scrambling ID. The UE can beconfigured or controlled by the network entity to perform PDSCHdescrambling using the legacy method or the descrambling methoddescribed above. This configuration/control can be semi-static (i.e.signaled by a higher layer), for example, via transmission modeconfiguration. Table 8 provides one example of an illustration of ahigher layer configuration of the PDSCH scrambling method.

TABLE 8 Higher layer signaling PDSCH scrambling method 0 Legacyscrambling method 1 Scrambled with the port scrambling ID

In other embodiments, the configuration or control can also be dynamic.For example, the UE may switch between the legacy method and the methodof descrambling using the port scrambling ID, depending on the controlinformation received from PDCCH or ePDCCH. In One example, the dynamiccontrol may be indicated using 1-bit signaling in the DCI format (for DLassignment). For example, a “0” indicates the legacy method should beused to receive the corresponding PDSCH, and a “1” indicates that methodof descrambling using the port scrambling ID should be used to receivethe corresponding PDSCH. In another example, the DM-RS ports assigned orthe rank assigned. For example, if the DM-RS port(s) assigned are 7, 7and 8, 9, 9 and 10, or, more generally, if the rank assigned is lessthan or equal to some specified number x where x can e.g. be 2, the portscrambling ID method is used (i.e., MU-MIMO operation may be assumed).Otherwise, the UE assumes that the legacy method is used (i.e., SU-MIMOoperation may be assumed).

In another example, the type of DCI format may be used to indicate thePDSCH scrambling method. For example, if DCI format 1A is received, thelegacy method is assumed to be used to descramble the correspondingPDSCH, else if DCI format 2C (or reference DCI format) is received, theport scrambling ID method is used to descramble the corresponding PDSCH.In another example, further dependency on where the DCI format wasreceived may be used to indicate the PDSCH scrambling method. Forexample, if the DCI format 1A was received in the common search space ofthe PDCCH/ePDCCH region, then the legacy method is used to descramblethe corresponding PDSCH, else if the DCI format 1A was received in theUE-specific search space of the PDCCH/ePDCCH region, then the portscrambling ID method is used to descramble the corresponding PDSCH. Thedynamic control methods above assume the UE is already configuredbeforehand (higher-layer e.g. RRC) to apply the dynamic control methods.

One benefit of scrambling PDSCH with port scrambling ID instead of theC-RNTI may include facilitation of MU-interference cancellation and/orsuppression for PDSCH. For example, given that the UE knows the portscrambling ID of the UE, as well as the port scrambling ID of theinterfering UE, the port scrambling ID method allows the UE todescramble and then decode the interfering PDSCH, which can then be usedfor interference cancellation/suppression as discussed above, forexample, with regard to the feedback loop 730 in FIG. 7 .

In various embodiments, the signaling of the port scrambling IDsignaling may include a predefined port scrambling ID for each DM-RSport. Table 9 illustrates one example of a mapping for 8 ports. However,mapping for fewer numbers of DM-RS ports is also possible (e.g. justports 7, 8, 9, and 10).

TABLE 9 DM-RS port index Port scrambling ID 7 000 8 001 9 010 10 011 11100 12 101 13 110 14 111

In this example, if the UE is signaled or detects blindly theinterfering UE's port(s), the UE is able to derive the port scramblingID used for the PDSCH of the interfering UE.

In another example, a higher layer configuration of port scrambling IDfor each DM-RS port (e.g. via an RRC) may be used to indicated the portscrambling ID to the UE. Table 10 illustrates one example of a mappingfor 8 ports. However, mapping for fewer numbers of DM-RS ports is alsopossible (e.g. just ports 7, 8, 9, and 10). For example, the number ofbits for the ID value can be log, (number of DM-RS ports) (i.e., 3 for 8ports and 2 for 4 ports) or the number of bits may be of the same lengthas the C-RNTI (i.e., 16 bits).

TABLE 10 DM-RS port index Port scrambling ID 7 A 8 B 9 C 10 D 11 E 12 F13 G 14 H

In this example, if the UE is signaled or detects blindly theinterfering UE's port(s), the UE is able to derive the port scramblingID used for the PDSCH of the interfering UE. In some embodiments, thehigher layering signaling of Table 10 is common for all MU UEs may bebroadcasted. In other embodiments (e.g., if the configuration and theconfigured value are UE-specific), the UE should also be signaled theport-scrambling ID of the interfering UE or the UE should blindly detectthe port scrambling ID of the interfering UE. Signaling of the DM-RSport scrambling ID of the interfering UE has significantly loweroverhead than signaling of C-RNTI. For example, if 8 ports are defined,only 3 bits are required for signaling of the DM-RS port scrambling ID,compared to 16 bits for C-RNTI signaling.

FIG. 9 illustrates a process for identifying resource scheduling for aUE in a multiple-user multiple-input multiple-output wirelesscommunication system in accordance with various embodiments of thepresent disclosure. For example, the process depicted in FIG. 9 may beperformed by the receiver 310 in FIG. 3 . The process may also beimplemented by the UE 700 in FIG. 7 .

The process begins by the UE receiving downlink control information(step 905). For example, in step 905, the UE may receive downlinkcontrol information in control signaling in a DCI format. The downlinkcontrol information may be statically or semi-statically signaled.Alternatively, the downlink control information may be dynamicallysignaled, for example, in each downlink subframe. The UE then identifiesDM-RS port(s) assigned to the UE (step 910). For example, in step 910,the UE may identify the DM-RS port(s) for the UE in the downlink controlinformation.

The UE then identifies a PDSCH EPRE to DM-RS EPRE ratio (step 915). Forexample, in step 915, the UE may identify the PDSCH EPRE to DM-RS EPREratio and whether rate matching is used from a jointly encoded signalbit field in the downlink control information. For example, the UE mayidentify the PDSCH EPRE to DM-RS EPRE ratio as 0 dB or −3 dB. The UE mayalso identify a number layers, a scrambling identifier, and whether ratematching is used from a jointly encoded message in the downlink controlinformation. The UE may also identify information about one or moreinterfering UEs including at least one of a modulation and coding schemeof the one or more interfering UEs, one or more port(s) assigned to theone or more interfering UEs, a number of the one or more interferingUEs, a UE identifier for the one or more interfering UEs, or a DM-RSport scrambling identifier for the one or more interfering UEs. The UEmay also identify a DM-RS port scrambling identifier for a DM-RS portassigned to an interfering UE to use to calculate an initializationvalue for a scrambling sequence for resources assigned to theinterfering UE and reduce interference. The UE may also identify whetheran interfering UE is allocated a group of resource blocks that overlapswith resource blocks assigned to the UE to reduce interference.

The UE then receives a downlink subframe (step 920). The UE thenidentifies resource block(s) including data intended for the UE (step925). The UE then identifies the data intended for the UE in theresource block (step 930). For example, in step 930, the UE may identifythe data using the one or more DM-RS port(s) and the PDSCH EPRE to DM-RSEPRE ratio. The resource block in the downlink subframe may include datafor multiple users in the wireless communication system. Thereafter, theUE returns to step 920 to receive and decode data from additionaldownlink subframes.

FIG. 10 illustrates a process for scheduling resources in amultiple-user multiple-input multiple-output wireless communicationsystem in accordance with various embodiments of the present disclosure.For example, the process depicted in FIG. 10 may be performed by thetransmitter 305 in FIG. 3 . The process may also be implemented by anetwork entity, such as an eNB, RRH, relay station, underlay basestation, GW, or BSC.

The process begins by the network entity identifying DM-RS port(s) toassign to the UE (step 1005). The network entity then identifies a PDSCHEPRE to DM-RS EPRE ratio (step 1010). For example, in step 1010, thenetwork entity may use the PDSCH EPRE to DM-RS EPRE ratio to multiplexdata in a same frequency resource.

The network entity then sends downlink control information (step 1015).For example, in step 1015, the network entity may send the controlinformation to the UE to indicate the DM-RS port(s) and PDSCH EPRE toDM-RS EPRE ratio. The downlink control information may be statically orsemi-statically signaled. Alternatively, the downlink controlinformation may be dynamically signaled, for example, in each downlinksubframe. In one example, the PDSCH EPRE to DM-RS EPRE ratio and whetherrate matching is used may be jointly encoded into a signal bit field inthe downlink control information. The one or more DM-RS port(s) assignedto the UE, a number layers, a scrambling identifier, the PDSCH EPRE toDM-RS EPRE ratio, and whether rate matching is used may be jointlyencoded in the downlink control information. The downlink controlinformation may include an indication of information about one or moreinterfering UEs including at least one of a modulation and coding schemeof the one or more interfering UEs, one or more port(s) assigned to theone or more interfering UEs, a number of the one or more interferingUEs, a UE identifier for the one or more interfering UEs, or a DM-RSport scrambling identifier for the one or more interfering UEs. Thedownlink control information may include an indication of a DM-RS portscrambling identifier for a DM-RS port assigned to an interfering UE.The downlink control information may include an indication of aninitialization value for a scrambling sequence for resources assigned tothe interfering UE using the DM-RS port scrambling identifier. Thedownlink control information may include an indication of whether aninterfering UE is allocated a group of resource blocks that overlapswith resource blocks assigned to the UE.

The network entity then transmits downlink subframes in accordance withthe scheduled resources (step 1020). For example, in step 1020, thenetwork entity may transmit the downlink subframes according to the oneor more DM-RS port(s) assigned to the UE and the PDSCH EPRE to DM-RSEPRE ratio.

Although FIGS. 9 and 10 illustrate examples of processes for schedulingresources and identifying resource scheduling in a MU-MIMO wirelesscommunication system, respectively, various changes could be made toFIGS. 9 and 10 . For example, while shown as a series of steps, varioussteps in each figure could overlap, occur in parallel, occur in adifferent order, or occur multiple times.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method for identifying resource scheduling for a user equipment (UE) in a multiple-user multiple-input multiple-output wireless communication system, the method comprising: receiving downlink control information indicating one or more demodulation reference signal (DM-RS) ports assigned to the UE, a number of layers, a scrambling identifier (SCID), and a physical downlink shared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPRE ratio; identifying, from the downlink control information, the one or more demodulation reference signal (DM-RS) ports assigned to the UE and a physical downlink shared channel ( the PDSCH) energy per resource element ( EPRE) to DM-RS EPRE ratio according to the number of layers; and identifying distinguishing a signal including data intended for the UE in a resource block in a downlink subframe from another signal for an interfering UE in the resource block including data intended for another the interfering UE using the SCID for the one or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio, wherein the resource block in the downlink subframe includes data for multiple users in the wireless communication system, and identifying, from the downlink control information, a DM-RS port SCID for a DM-RS port assigned to the interfering UE; identifying an initialization value for a scrambling sequence for resources assigned to the interfering UE using the DM-RS port SCID; and reducing interference from the interfering UE in identifying the data intended for the UE in the resource block using the initialization value for the scrambling sequence for resources assigned to the interfering UE.
 2. The method of claim 1, wherein the UE is assigned ports from one DM-RS code division multiplexing (CDM) group, the method further comprising: identifying the PDSCH EPRE to DM-RS EPRE ratio and whether rate matching around another DM-RS CDM group is used from a jointly encoded signal bit field in the downlink control information.
 3. The method of claim 1, wherein identifying the one or more DM-RS ports assigned to the UE and the PDSCH EPRE to DM-RS EPRE ratio comprises identifying the one or more DM-RS ports assigned to the UE, a number layers, a scrambling identifier, the PDSCH EPRE to DM-RS EPRE ratio, and whether rate matching is used from a jointly encoded message in the downlink control information is 0 decibels (dB) or −3 dB.
 4. The method of claim 1, further comprising: identifying, from the downlink control information, information about one or more interfering UEs including at least one of a modulation and coding scheme of the one or more interfering UEs, one or more ports assigned to the one or more interfering UEs, a number of the one or more interfering UEs, a UE identifier for the one or more interfering UEs, or a DM-RS port scrambling identifier for the one or more interfering UEs; and reducing interference from at least one of the one or more interfering UEs in identifying the data intended for the UE in the resource block using the information about one or more interfering UEs.
 5. The method of claim 1 further comprising: identifying, from the downlink control information, a DM-RS port scrambling identifier fora DM-RS port assigned to an interfering UE; identify an initialization value for a scrambling sequence for resources assigned to the interfering UE using the DM-RS port scrambling identifier; and reducing interference from the interfering UE in identifying the data intended for the UE in the resource block using the initialization value for the scrambling sequence for resources assigned to the interfering UE.
 6. The method of claim 1, further comprising: identifying, from the downlink control information, whether an interfering UE is allocated a group of resource blocks that overlaps with resource blocks assigned to the UE; and reducing interference from the interfering UE in the group of resource blocks that overlaps with resource blocks assigned to the UE in identifying the data intended for the UE.
 7. A method for scheduling resources in a multiple-user multiple-input multiple-output wireless communication system, the method comprising: identifying one or more demodulation reference signal (DM-RS) ports to assign to a UE and a physical downlink shared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPRE ratio for identifying a signal including data intended for the UE in a resource block in a downlink subframe from another signal in the resource block including data intended for another UE; and including an indication of the one or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio in downlink control information, wherein the resource block in the downlink subframe includes data for multiple users in the wireless communication system.
 8. The method of claim 7, wherein including the indication of the one or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio in the downlink control information comprises jointly encoding an indication of the one or more DM-RS ports assigned to the UE, a number layers, a scrambling identifier, the PDSCH EPRE to DM-RS EPRE ratio, and whether rate matching is used from in the downlink control information.
 9. The method of claim 7 further comprising including, in the downlink control information, information about one or more interfering UEs including at least one of a modulation and coding scheme of the one or more interfering UEs, one or more ports assigned to the one or more interfering UEs, a number of the one or more interfering UEs, a UE identifier for the one or more interfering UEs, or a DM-RS port scrambling identifier for the one or more interfering UEs for reducing interference from at least one of the one or more interfering UEs.
 10. The method of claim 7 further comprising including, in the downlink control information, whether an interfering UE is allocated a group of resource blocks that overlaps with resource blocks assigned to the n for reducing interference from the interfering UE in the group of resource blocks that overlaps with resource blocks assigned to the UE.
 11. An apparatus configured to identify resource scheduling for a user equipment (UE) in a multiple-user multiple-input multiple-output wireless communication system, the apparatus comprising: a receiver configured to receive downlink control information indicating one or more demodulation reference signal (DM-RS) ports assigned to the UE, a number of layers, and a scrambling identifier (SCID), and a physical downlink shared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPRE ratio; and a controller configured to: identify, from the downlink control information, the one or more demodulation reference signal (DM-RS) ports assigned to the UE, the number of layers, the SCID, and a physical downlink shared channel ( the PDSCH) energy per resource element ( EPRE) to DM-RS EPRE ratio according to the number of layers, and identifydistinguish a signal including data intended for the UE in a resource block in a downlink subframe from another signal in the resource block including data intended for another UE using the SCID for the one or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio, wherein the resource block in the downlink subframe includes data for multiple users in the wireless communication system, wherein the controller is configured to identify, from the downlink control information, an SCID for a DM-RS port assigned to an interfering UE, and identify an initialization value for a scrambling sequence for resources assigned to the interfering UE using the DM-RS port SCID, the apparatus further comprising: control receiver processing circuitry configured to reduce interference from the interfering UE in identifying the data intended for the UE in the resource block using the initialization value for the scrambling sequence for resources assigned to the interfering UE.
 12. The apparatus of claim 11, wherein the UE is assigned ports from one DM-RS code division multiplexing (CDM) group, and wherein the controller is configured to identify the PDSCH EPRE to DM-RS EPRE ratio and whether rate matching around another DM-RS CDM group is used from a jointly encoded signal bit field in the downlink control information.
 13. The apparatus of claim 11, wherein in identifying the one or more DM-RS ports assigned to the UE and the PDSCH EPRE to DM-RS EPRE ratio, the controller is configured to identify the one or more DM-RS ports assigned to the UE, a number layers, a scrambling identifier, the PDSCH EPRE to DM-RS EPRE ratio, and whether rate matching is used from a jointly encoded message in the downlink control information is 0 decibels (dB) or −3 dB.
 14. The apparatus of claim 11, wherein the controller is configured to: identify, from the downlink control information, information about one or more interfering UEs including at least one of a modulation and coding scheme of the one or more interfering UEs, one or more ports assigned to the one or more interfering UEs, a number of the one or more interfering UEs, a UE identifier for the one or more interfering UEs, or a DM-RS port scrambling identifier for the one or more interfering UEs; and, the apparatus further comprising: control receiver processing circuitry configured to reduce interference from at least one of the one or more interfering UEs in identifying the data intended for the UE in the resource block using the information about one or more interfering UEs.
 15. The apparatus of claim 11, wherein the controller is configured to: identify, from the downlink control information, a DM-RS port scrambling identifier for a DM-RS port assigned to an interfering UE; identify an initialization value for a scrambling sequence for resources assigned to the interfering UE using the DM-RS port scrambling identifier; and control receiver processing circuitry to reduce interference from the interfering UE in identifying the data intended for the UE in the resource block using the initialization value for the scrambling sequence for resources assigned to the interfering UE.
 16. The apparatus of claim 11, wherein the controller is configured to: identify, from the downlink control information, whether an interfering UE is allocated a group of resource blocks that overlaps with resource blocks assigned to the UE; and, the apparatus further comprising: control receiver processing circuitry configured to reduce interference from the interfering UE in the group of resource blocks that overlaps with resource blocks assigned to the UE in identifying the data intended for the UE.
 17. An apparatus configured to schedule resources in a multiple-user multiple-input multiple-output wireless communication system, the apparatus comprising: a transmitter; and a controller configured to: identify one or more demodulation reference signal (DM-RS) ports to assign to a UE and a physical down- link shared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPRE ratio for identifying a signal including data intended for the UE in a resource block in a downlink subframe from another signal in the resource block including data intended for another UE, and control the transmitter to include an indication of the one or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio in downlink control information, wherein the resource block in the downlink subframe includes data for multiple users in the wireless communication system.
 18. The apparatus of claim 17, wherein in controlling the transmitter to include the indication of the one or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio in the downlink control information, the controller is configured to control the transmitter to jointly encode an indication of the one or more DM-RS ports assigned to the UE, a number layers, a scrambling identifier, the PDSCH EPRE to DM-RS EPRE ratio, and whether rate matching is used from in the downlink control information.
 19. The apparatus of claim 17, wherein the controller is configured to control the transmitter to include, in the downlink control information, information about one or more interfering UEs including at least one of a modulation and coding scheme of the one or more interfering UEs, one or more ports assigned to the one or more interfering UEs, a number of the one or more interfering UEs, a UE identifier for the one or more interfering UEs, or a DM-RS port scrambling identifier for the one or more interfering UEs for reducing interference from at least one of the one or more interfering UEs.
 20. The apparatus of claim 17, wherein the controller is configured to control the transmitter to include, in the downlink control information, whether an interfering UE is allocated a group of resource blocks that overlaps with resource blocks assigned to the UE for reducing interference from the interfering UE in the group of resource blocks that overlaps with resource blocks assigned to the UE.
 21. A method for identifyinq resource scheduling for a user equipment (UE) in a multiple-user multiple-input multiple-output wireless communication system, the method comprising: receiving downlink control information; receiving data in a resource block in a downlink subframe according to a bit field in the downlink control information, wherein the downlink control information indicates one or more demodulation reference signal (DM-RS) ports assigned to the UE, a number of layers, a scrambling identifier, a physical downlink shared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPRE ratio, and whether rate matching around at least one port unassigned to the UE and in a DM-RS code division multiplexing (CDM) group is used, wherein: for a first value of the bit field, (i) one or more first DM-RS ports included in a first DM-RS CDM group are assigned to the UE, (ii) a PDSCH EPRE to DMRS EPRE ratio has a value of 0 dB, and (iii) the data siqnal is mapped to the resource for a second DM-RS CDM qroup unassiqned to the UE, for a second value of the bit field, (i) one or more second DM-RS ports included in the first DM-RS CDM group are assigned to the UE, (ii) the PDSCH EPRE to DM-RS EPRE ratio has a value of −3 dB, and (iii) the data siqnal is not mapped to the resource for the second DM-RS CDM group unassigned to the UE, for a third value of the bit field, (i) one or more third DM-RS ports included in the second DM-RS CDM group are assigned to the UE, (ii) the PDSCH EPRE to DM-RS EPRE ratio has the value of −3 dB, and (iii) the data siqnal is not mapped to the resource for the first DM-RS CDM group unassigned to the UE, and for a fourth value of the bit field, (i) both one or more fourth DM-RS ports included in the first DM-RS CDM group and one or more fifth DM-RS ports included in the second DM-RS CDM group are assigned to the UE, and (ii) the PDSCH EPRE to DM-RS EPRE ratio has the value of −3 dB; and identifying data intended for the UE in the resource block in the downlink subframe using the one or more DM-RS ports assigned to the UE and the PDSCH EPRE to DM-RS EPRE ratio, wherein the resource block in the downlink subframe includes data for multiple users in the wireless communication system.
 22. The method of claim 21, wherein the PDSCH EPRE to DMRS EPRE ratio is 0 decibels (dB) to −3 dB.
 23. The method of claim 21, further comprising: identifying, from the downlink control information, information about one or more interfering UEs including at least one of a modulation and coding scheme of the one or more interfering UEs, one or more ports assigned to the one or more interfering UEs, a number of the one or more interfering UEs, a UE identifier for the one or more interfering UEs, or a DM-RS port scrambling identifier for the one or more interfering UEs.
 24. The method of claim 21, further comprising: identifying, from the downlink control information, whether an interfering UE is allocated a group of resource blocks that overlaps with resource blocks assigned to the UE.
 25. A method for identifying resource scheduling for a user equipment (UE) in a multiple-user multiple-input multiple-output wireless communication system, the method comprising: receiving downlink control information indicating one or more demodulation reference signal (DM-RS) ports assigned to the UE, a number of layers, a scrambling identifier (SCID), and a physical downlink shared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPRE ratio; identifying, from the downlink control information, the one or more DM-RS ports assigned to one or more UE(s) and the PDSCH EPRE to DM-RS EPRE ratio according to the number of layers; receiving a signal including one or more layers in at least one resource block, wherein the signal comprises a UE-specific signal identifiable from signals for one or more other UEs based on SCID(s) for the one or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio, wherein a layer is associated with a DM-RS port; identifying, from the downlink control information, a DM-RS port SCID for a DM-RS port assigned to one of one or more other UEs; identify an initialization value for a scrambling sequence for resources assigned to the one of the one or more other UEs using the DM-RS port SCID; and reducing interference from the one of the one or more other UEs in identifying data intended for the UE in the resource block using the initialization value for the scrambling sequence for resources assigned to the one of the one or more other UEs.
 26. The method of claim 25, further comprising: identify an initialization value for a scrambling identifier for resources assigned to one of the one more interfering UEs using the scrambling identifier.
 27. A method for scheduling resources for a user equipment (UE) in a multiple-user multiple-input multiple-output wireless communication system, the method comprising: identifying one or more demodulation reference signal (DM-RS) ports to assign to the UE and a physical downlink shared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPRE ratio for identifying data intended for the UE in a resource block in a downlink subframe; including an information indicating the one or more DM-RS ports assigned to the UE, a number of layers, a scrambling identifier, the PDSCH EPRE to DM-RS EPRE ratio, and whether rate matching around one or more ports from a DM-RS code division multiplexing (CDM) group unassigned to the UE is used in downlink control information; transmitting the downlink control information; and transmitting the data intended for the UE in the resource block in the downlink subframe according to a bit field in the downlink control information, wherein: for a first value of the bit field, (i) one or more first DMRS ports included in a first DMRS CDM group are assigned to the UE, (ii) a PDSCH EPRE to DMRS EPRE ratio has a value of 0 dB, and (iii) the data signal is mapped to the resource for a second DMRS CDM group unassigned to the UE, for a second value of the bit field, (i) one or more second DMRS ports included in the first DMRS CDM group are assigned to the UE, (ii) the PDSCH EPRE to DM-RS EPRE ratio has a value of −3 dB, and (iii) the data signal is not mapped to the resource for the second DMRS CDM group unassigned to the UE, for a third value of the bit field, (i) one or more third DMRS ports included in the second DMRS CDM group are assigned to the UE, (ii) the PDSCH EPRE to DM-RS EPRE ratio has the value of −3 dB, and (iii) the data signal is not mapped to the resource for the first DMRS CDM group unassigned to the UE, and for a fourth value of the bit field, (i) both one or more fourth DMRS ports included in the first DMRS CDM group and one or more fifth DMRS ports included in the second DMRS CDM group are assigned to the UE, and (ii) the PDSCH EPRE to DMRS EPRE ratio has the value of −3 dB, wherein the resource block in the downlink subframe includes the data for multiple users in the wireless communication system.
 28. The method of claim 27, further comprising including, in the downlink control information, information about one or more interfering UEs including at least one of a modulation and coding scheme of the one or more interfering UEs, one or more ports assigned to the one or more interfering UEs, a number of the one or more interfering UEs, a UE identifier for the one or more interfering UEs, or a DM-RS port scrambling identifier for the one or more interfering UEs.
 29. A method for scheduling resources for a user equipment (UE) in a multiple-user multiple-input multiple-output wireless communication system, the method comprising: identifying one or more demodulation reference signal (DM-RS) ports to assign to the UE and a physical downlink shared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPRE ratio for identifying data intended for the UE in a resource block in a downlink subframe; including an information related to the one or more DM-RS ports assigned to the UE, a number of layers, a scrambling identifier, the PDSCH EPRE to DM-RS EPRE ratio, and whether rate matching around one or more ports from a DM-RS code division multiplexing (CDM) group unassigned to the UE is used in downlink control information; including, in the downlink control information, whether an interfering UE is allocated a group of resource blocks that overlaps with resource blocks assigned to the UE; transmitting the downlink control information; and transmitting the data intended for the UE in the resource block in the downlink subframe based on a case determined among four cases according to a bit field in the downlink control information, wherein the four cases include: a first case that (i) one or more first DMRS ports included in a first DMRS CDM group are assigned to the UE, (ii) a PDSCH EPRE to DMRS EPRE ratio has a value of 0 dB, (iii) the data signal is mapped to the resource for a second DMRS CDM group unassigned to the UE, a second case that (i) one or more second DMRS ports included in the first DMRS CDM group are assigned to the UE, (ii) the PDSCH EPRE to DM-RS EPRE ratio has a value of −3 dB, and (iii) the data signal is not mapped to the resource for the second DMRS CDM group unassigned to the UE, a third case that (i) one or more third DMRS ports included in the second DMRS CDM group are assigned to the UE, (ii) the PDSCH EPRE to DM-RS EPRE ratio has the value of −3 dB, and (iii) the data signal is not mapped to the resource for the first DMRS CDM group unassigned to the UE, and a fourth case that (i) both one or more fourth DMRS ports included in the first DMRS CDM group and one or more fifth DMRS ports included in the second DMRS CDM group are assigned to the UE, and (ii) the PDSCH EPRE to DMRS EPRE ratio has the value of −3 dB, wherein the resource block in the downlink subframe includes the data for multiple users in the wireless communication system.
 30. An apparatus configured to identify resource scheduling for a user equipment (UE) in a multiple-user multiple-input multiple-output wireless communication system, the apparatus comprising: a receiver configured to receive downlink control information including a bit field related to an antenna port; and receive data in a resource block in a downlink subframe according to a bit field in the downlink control information, wherein the downlink control information indicates one or more demodulation reference signal (DM-RS) ports assigned to the UE, a number of layers, a scrambling identifier, a physical downlink shared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPRE ratio, and whether rate matching around at least one port unassigned to the UE and in a DM-RS code division multiplexing (CDM) group is used, wherein: for a first value of the bit field, (i) one or more first DM-RS ports included in a first DM-RS CDM group are assigned to the UE, (ii) a PDSCH EPRE to DMRS EPRE ratio has a value of 0 dB, and (iii) the data signal is mapped to the resource for a second DM-RS CDM group unassigned to the UE, for a second value of the bit field, (i) one or more second DM-RS ports included in the first DM-RS CDM group are assigned to the UE, (ii) the PDSCH EPRE to DM-RS EPRE ratio has a value of −3 dB, and (iii) the data signal is not mapped to the resource for the second DM-RS CDM group unassigned to the UE, for a third value of the bit field, (i) one or more third DM-RS ports included in the second DM-RS CDM group are assigned to the UE, (ii) the PDSCH EPRE to DM-RS EPRE ratio has the value of −3 dB, and (iii) the data signal is not mapped to the resource for the first DM-RS CDM group unassigned to the UE, and for a fourth value of the bit field, (i) both one or more fourth DM-RS ports included in the first DM-RS CDM group and one or more fifth DM-RS ports included in the second DM-RS CDM group are assigned to the UE, and (ii) the PDSCH EPRE to DM-RS EPRE ratio has the value of −3 dB; and a controller configured to identify data intended for the UE in a resource block in a downlink subframe using the one or more DM-RS ports assigned to the UE and the PDSCH EPRE to DM-RS EPRE ratio, wherein the resource block in the downlink subframe includes data for multiple users in the wireless communication system.
 31. The apparatus of claim 30, wherein the PDSCH EPRE to DMRS EPRE ratio is 0 decibels (dB) to −3 dB.
 32. The apparatus of claim 30, wherein the controller is configured to identify, from the downlink control information, whether an interfering UE is allocated a group of resource blocks that overlaps with resource blocks assigned to the UE.
 33. The apparatus of claim 30, wherein the controller is configured to identify, from the downlink control information, information about one or more interfering UEs including at least one of a modulation and coding scheme of the one or more interfering UEs, one or more ports assigned to the one or more interfering UEs, a number of the one or more interfering UEs, a UE identifier for the one or more interfering UEs, or a DM-RS port scrambling identifier for the one or more interfering UEs.
 34. An apparatus configured to identify resource scheduling for a user equipment (UE) in a multiple-user multiple-input multiple-output wireless communication system, the apparatus comprising: a receiver configured to receive downlink control information indicating one or more demodulation reference signal (DM-RS) ports assigned to the UE, a number of layers, a scrambling identifier (SCID), and a physical downlink shared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPRE ratio; and a controller configured to: identify, from the downlink control information, the one or more DM-RS ports assigned to one or more UE(s) and the PDSCH EPRE to DM-RS EPRE ratio according to the number of layers, and receive, via the receiver, a signal including one or more layers in at least one resource block, wherein the signal comprises a UE-specific signal identifiable based on SCID(s) for the one or more DM-RS ports and the PDSCH EPRE to DM-RS EPRE ratio, wherein a layer is associated with a DM-RS port, identify, from the downlink control information, a DM-RS port scrambling identifier for a DM-RS port assigned to one of one or more other UEs, identify an initialization value for a scrambling sequence for resources assigned to the one of the one or more other UEs using the DM-RS port scrambling identifier, and control the receiver to reduce interference from the one of the one or more other UEs in identifying data intended for the UE in the resource block using the initialization value for the scrambling sequence for resources assigned to the one of the one or more other UEs.
 35. The apparatus of claim 34, wherein the controller is configured to identify an initialization value for a scrambling identifier for resources assigned to one of the one more interfering UEs using the scrambling identifier.
 36. An apparatus configured to schedule resources for a user equipment (UE) in a multiple-user multiple-input multiple-output wireless communication system, the apparatus comprising: a controller configured to: identify one or more demodulation reference signal (DM-RS) ports to assign to a UE and a physical downlink shared channel (PDSCH) energy per resource element (EPRE) to DM-RS EPRE ratio for identifying data intended for the UE in a resource block in a downlink subframe, and include an information related to the one or more DM-RS ports assigned to the UE, a number of layers, a scrambling identifier, the PDSCH EPRE to DM-RS EPRE ratio, and whether rate matching around one or more ports from a DM-RS code division multiplexing (CDM) group unassigned to the UE is used in downlink control information; and a transmitter coupled with the controller, wherein the transmitter is configured to transmit the downlink control information, and a transmitter coupled with the controller, wherein the transmitter is condigured to transmit the downlink control information, and transmit the data intended for the UE in the resource block in the downlink subframe based on a case determined among four cases according to a bit field in the downlink control information, wherein the four cases include: a first case that (i) one or more first DMRS ports included in a first DMRS CDM group are assigned to the UE, (ii) a PDSCH EPRE to DMRS EPRE ratio has a value of 0 dB, (iii) the data signal is mapped to the resource for a second DMRS CDM group unassigned to the UE, a second case that (i) one or more second DMRS ports included in the first DMRS CDM group are assigned to the UE, (ii) the PDSCH EPRE to DM-RS EPRE ratio has a value of −3 dB and (iii) the data signal is not mapped to the resource for the second DMRS CDM group unassigned to the UE, a third case that (i) one or more third DMRS ports included in the second DMRS CDM group are assigned to the UE, (ii) the PDSCH EPRE to DM-RS EPRE ratio has the value of −3 dB and (iii) the data signal is not mapped to the resource for the first DMRS CDM group unassigned to the UE, and a fourth case that (i) both one or more fourth DMRS ports included in the first DMRS CDM group and one or more fifth DMRS ports included in the second DMRS CDM group are assigned to the UE, and (ii) the PDSCH EPRE to DMRS EPRE ratio has the value of −3 dB, wherein the resource block in the downlink subframe includes the data for multiple users in the wireless communication system.
 37. The apparatus of claim 36, wherein the controller is configured to include, in the downlink control information, information about one or more interfering UEs including at least one of a modulation and coding scheme of the one or more interfering UEs, one or more ports assigned to the one or more interfering UEs, a number of the one or more interfering UEs, a UE identifier for the one or more interfering UEs, or a DM-RS port scrambling identifier for the one or more interfering UEs.
 38. The apparatus of claim 37, wherein the controller is configured to include, in the downlink control information, whether an interfering UE is allocated a group of resource blocks that overlaps with resource blocks assigned to the UE. 